As a capacitor having a small size, a large capacitance, and low ESR (Equivalent Series Resistance), one of promising candidates is an electrolytic capacitor including an anode foil on which a dielectric layer is formed, a solid electrolyte layer formed so as to cover at least a part of the dielectric layer, and an electrolyte solution. For example, Unexamined Japanese Patent Publication No. 2009-111174 discloses an electrolytic capacitor obtained by impregnating a solid electrolyte layer with a solvent containing, for example, γ-butyrolactone or sulfolane.
Further, for example, Unexamined Japanese Patent Publication No. 2004-128048 discloses an electrolytic capacitor including an anode foil, a solid electrolyte layer, and a cathode foil on which a coating film made of a metal nitride or a metal is formed.